New review comment by Johnnynator on void-packages repository

https://github.com/void-linux/void-packages/pull/33137#discussion_r716244895

Comment:
Add this in do_install and replace your occurrences of XBPS_MACHINE with arch, this is mainly what we set in the cmake build-style, but i686 changed to i366 instead of x86
```
case $XBPS_TARGET_ARCH in
	arm*) arch=arm;;
	aarch64*) arch=aarch64;;
	i686*) arch=i386;;
	mips*) arch=mips;;
	x86_64*) arch=x86_64;;
	ppc64le*) arch=ppc64le;;
	ppc64*) arch=ppc64;;
	ppcle*) arch=ppcle
	ppc*) arch=ppc
	*) arch="generic"
esac
```